This work is concerned with genetic control of the variety of functions influenced by the mating-type locus in the yeast Saccharomyces cerevisiae. Mutants have been isolated on the basis of a variety of mating-type related phenotypes and are being analyzed genetically and physiologically. The functions of particular interest, in addition to conjugation, are production and response to diffusible hormone-like factors, and sexual agglutination. BIBLIOGRAPHIC REFERENCES: Manney, Thomas R. and Verna Woods, Mutants of Saccharomyces cerevisiae resistant to the alpha mating-type factor. Genetics 82: 639-644, 1976.